Only wait for recent newPayload calls

src/config.rs

@@ -53,6 +53,12 @@ pub struct Config {
     /// the behaviour of a full execution engine.
     #[arg(long, value_name = "MILLIS", default_value = "2000")]
     pub new_payload_wait_millis: u128,
+    /// Maximum age of a payload that will trigger a wait on `newPayload`
+    ///
+    /// Payloads older than this age receive an instant SYNCING response. See docs for
+    /// `--new-payload-wait-millis` for the purpose of this wait.
+    #[arg(long, value_name = "NUM_BLOCKS", default_value = "64")]
+    pub new_payload_wait_cutoff: u64,
     /// Maximum time that a consensus node should wait for a forkchoiceUpdated response from the
     /// cache.
     ///

src/multiplexer.rs

@@ -19,7 +19,7 @@ use tokio::sync::Mutex;
 pub struct Multiplexer<E: EthSpec> {
     pub engine: Engine,
     pub fcu_cache: Mutex<LruCache<JsonForkchoiceStateV1, JsonPayloadStatusV1>>,
-    pub new_payload_cache: Mutex<LruCache<ExecutionBlockHash, JsonPayloadStatusV1>>,
+    pub new_payload_cache: Mutex<LruCache<ExecutionBlockHash, NewPayloadCacheEntry>>,
     pub justified_block_cache: Mutex<LruCache<ExecutionBlockHash, ()>>,
     pub finalized_block_cache: Mutex<LruCache<ExecutionBlockHash, ()>>,
     pub payload_builder: Mutex<PayloadBuilder<E>>,
@@ -30,6 +30,11 @@ pub struct Multiplexer<E: EthSpec> {
     _phantom: PhantomData<E>,
 }
 
+pub struct NewPayloadCacheEntry {
+    pub status: JsonPayloadStatusV1,
+    pub block_number: u64,
+}
+
 impl<E: EthSpec> Multiplexer<E> {
     pub fn new(config: Config, executor: TaskExecutor, log: Logger) -> Result<Self, String> {
         let engine: Engine = {

src/new_payload.rs

@@ -1,6 +1,6 @@
 //! Handler for new payload.
 use crate::{
-    multiplexer::Multiplexer,
+    multiplexer::{Multiplexer, NewPayloadCacheEntry},
     types::{
         ErrorResponse, JsonExecutionPayload, JsonPayloadStatusV1, JsonPayloadStatusV1Status,
         JsonValue, QuantityU64, Request, Response,
@@ -20,6 +20,7 @@ impl<E: EthSpec> Multiplexer<E> {
 
         // TODO: verify block hash
         let block_hash = *json_execution_payload.block_hash();
+        let block_number = *json_execution_payload.block_number();
 
         let status = if let Some(status) = self.get_cached_payload_status(&block_hash, true).await {
             status
@@ -31,10 +32,13 @@ impl<E: EthSpec> Multiplexer<E> {
                     let json_status = JsonPayloadStatusV1::from(status);
 
                     // Update newPayload cache.
-                    self.new_payload_cache
-                        .lock()
-                        .await
-                        .put(block_hash, json_status.clone());
+                    self.new_payload_cache.lock().await.put(
+                        block_hash,
+                        NewPayloadCacheEntry {
+                            status: json_status.clone(),
+                            block_number,
+                        },
+                    );
 
                     // Update payload builder.
                     self.register_canonical_payload(&execution_payload, json_status.status)
@@ -63,15 +67,19 @@ impl<E: EthSpec> Multiplexer<E> {
 
         // TODO: verify block hash
         let block_hash = execution_payload.block_hash();
-
-        // Wait a short time for a definite response from the EL. Chances are it's busy processing
-        // the payload sent by the controlling BN.
-        let start = Instant::now();
-        while start.elapsed().as_millis() < self.config.new_payload_wait_millis {
-            if let Some(status) = self.get_cached_payload_status(block_hash, true).await {
-                return Response::new(id, status);
+        let block_number = *execution_payload.block_number();
+
+        // If this is a *recent* payload, wait a short time for a definite response from the EL.
+        // Chances are it's busy processing the payload sent by the controlling BN.
+        let is_recent = self.is_recent_payload(block_number).await;
+        if is_recent {
+            let start = Instant::now();
+            while start.elapsed().as_millis() < self.config.new_payload_wait_millis {
+                if let Some(status) = self.get_cached_payload_status(block_hash, true).await {
+                    return Response::new(id, status);
+                }
+                tokio::time::sleep(Duration::from_millis(50)).await;
             }
-            tokio::time::sleep(Duration::from_millis(50)).await;
         }
 
         // Try again to get any status from the cache, or fall back on a SYNCING response.
@@ -81,7 +89,11 @@ impl<E: EthSpec> Multiplexer<E> {
             }
             status
         } else {
-            tracing::info!("sending SYNCING response on newPayload");
+            if is_recent {
+                tracing::info!("sending SYNCING response on recent newPayload");
+            } else {
+                tracing::info!("sending instant SYNCING response for old newPayload");
+            }
             // Synthetic syncing response.
             JsonPayloadStatusV1 {
                 status: JsonPayloadStatusV1Status::Syncing,
@@ -145,11 +157,32 @@ impl<E: EthSpec> Multiplexer<E> {
         definite_only: bool,
     ) -> Option<JsonPayloadStatusV1> {
         let mut cache = self.new_payload_cache.lock().await;
-        if let Some(existing_status) = cache.get(execution_block_hash) {
-            if !definite_only || Self::is_definite(existing_status) {
-                return Some(existing_status.clone());
+        if let Some(existing) = cache.get(execution_block_hash) {
+            if !definite_only || Self::is_definite(&existing.status) {
+                return Some(existing.status.clone());
             }
         }
         None
     }
+
+    /// Return the highest `block_number` of any cached payload, or 0 if none is cached.
+    ///
+    /// This is useful for approximately time-based cutoffs & heuristics.
+    pub async fn highest_cached_payload_number(&self) -> u64 {
+        let cache = self.new_payload_cache.lock().await;
+        cache
+            .iter()
+            .map(|(_, entry)| entry.block_number)
+            .max()
+            .unwrap_or(0)
+    }
+
+    /// Check if the given block number is recent based on the `highest_cached_payload_number`.
+    pub async fn is_recent_payload(&self, block_number: u64) -> bool {
+        let cutoff = self
+            .highest_cached_payload_number()
+            .await
+            .saturating_sub(self.config.new_payload_wait_cutoff);
+        block_number >= cutoff
+    }
 }